Nicola Sturgeon has been censured by the UK’s chief statistician after using incomplete and unpublished data to claim the coronavirus was five times less prevalent in Scotland than in England.
Ed Humpherson, the director general of the Office of Statistics Regulation, said Sturgeon’s claims earlier in July were not based on comparable or published data, and should not have been made. “The sources used to underpin this claim have been difficult to identify,” he told Sturgeon’s government.
In an official letter to Roger Halliday, the Scottish government’s chief statistician, Humpherson said he did not believe the sources used by Sturgeon were robust enough, following an investigation into complaints about the first minister’s statements.
After analysing the data sources given to him by Sturgeon’s officials, he told Halliday: “We do not think that the sources [provided] allow for a quantified and uncaveated comparison of the kind that was made. In future if such comparisons are made, we would expect to see sources made publicly available.”
Sturgeon said earlier this month that she was worried Scotland could be put at risk because of “shambolic” policies on foreign travel and air bridges then being pushed by ministers in England.
On 3 July, she said she would resist pressure to agree quickly to the UK government’s proposals for quarantine-free travel from other countries with low infection rates, because she wanted to ensure Scotland’s steep decline in Covid-19 cases was protected.
“When so much is at stake as it is right now, we can’t allow ourselves to be dragged along in the wake of another government’s, to be quite frank about it, shambolic decision-making process,” she said then.
Sturgeon went on to say: “We assess that the prevalence of the virus in Scotland, right now, is five times lower than it is in England. Northern Ireland actually faces a similar issue.
“So that means that there may well be cases where the UK government is admitting visitors to England without quarantine from countries that don’t present a significant risk of raising infection levels there, but would create that risk in Scotland.”
The Covid-19 pandemic is currently unfolding in “one big wave” with no evidence that it follows seasonal variations common to influenza and other coronaviruses, such as the common cold, the World Health Organization has warned.
Epidemics of infectious diseases behave in different ways but the 1918 influenza pandemic that killed more than 50 million people is regarded as a key example of a pandemic that occurred in multiple waves, with the latter more severe than the first. It has been replicated – albeit more mildly – in subsequent flu pandemics. Until now that had been what was expected from Covid-19.
How and why multiple-wave outbreaks occur, and how subsequent waves of infection can be prevented, has become a staple of epidemiological modelling studies and pandemic preparation, which have looked at everything from social behaviour and health policy to vaccination and the buildup of community immunity, also known as herd immunity.
Is there evidence of coronavirus coming back in a second wave?
This is being watched very carefully. Without a vaccine, and with no widespread immunity to the new disease, one alarm is being sounded by the experience of Singapore, which has seen a sudden resurgence in infections despite being lauded for its early handling of the outbreak.
Although Singapore instituted a strong contact tracing system for its general population, the disease re-emerged in cramped dormitory accommodation used by thousands of foreign workers with inadequate hygiene facilities and shared canteens.
Singapore’s experience, although very specific, has demonstrated the ability of the disease to come back strongly in places where people are in close proximity and its ability to exploit any weakness in public health regimes set up to counter it.
In June 2020, Beijing suffered from a new cluster of coronavirus cases which caused authorities to re-implement restrictions that China had previously been able to lift. In the UK, the city of Leicester was unable to come out of lockdown because of the development of a new spike of coronavirus cases. Clusters also emerged in Melbourne, requiring a re-imposition of lockdown conditions.
What are experts worried about?
Conventional wisdom among scientists suggests second waves of resistant infections occur after the capacity for treatment and isolation becomes exhausted. In this case the concern is that the social and political consensus supporting lockdowns is being overtaken by public frustration and the urgent need to reopen economies.
However Linda Bauld, professor of public health at the University of Edinburgh, says “‘Second wave’ isn’t a term that we would use at the current time, as the virus hasn’t gone away, it’s in our population, it has spread to 188 countries so far, and what we are seeing now is essentially localised spikes or a localised return of a large number of cases.”
The overall threat declines when susceptibility of the population to the disease falls below a certain threshold or when widespread vaccination becomes available.
In general terms the ratio of susceptible and immune individuals in a population at the end of one wave determines the potential magnitude of a subsequent wave. The worry is that with a vaccine still many months away, and the real rate of infection only being guessed at, populations worldwide remain highly vulnerable to both resurgence and subsequent waves.
Humpherson said that claim could not be substantiated. The Scottish government had used Scottish modelling done by its experts and then compared it against unpublished modelling from the London School of Hygiene and Tropical Medicine, which used a UK prevalence figure as a proxy for England. It then used other data from the Office for National Statistics which was based on a different time period and estimates than the Scottish data.
Humpherson said Sturgeon should have shared the sources and justification for her comparison because it used unpublished data.
“There are lessons to be learnt in this case, with different data sources being quoted to the media and to us. We expect that any figures used are appropriately sourced, explained and available in the public domain,” he said.
“It is important to recognise that a comparison of Covid-19 prevalence rates is not straightforward. If it is to be undertaken, the results and the uncertainties should be communicated transparently. [In] future if such comparisons are made, we would expect to see sources made publicly available and a clear explanation of the limitations and associated uncertainty.”
In a further letter about the figures, David Norgrove, the chairman of the UK Statistics Authority, told the Tory MSP Miles Briggs that the sources given by the Scottish government to justify Sturgeon’s assertion “do not allow for a meaningful comparison to be made”.
Briggs, the Scottish Conservatives shadow health secretary, said Sturgeon should apologise for using misleading data. He said it had inflamed border tensions with England and was wrongly used to justify keeping Scottish businesses closed for longer than necessary.
“The first minister’s use of these dodgy statistics even led to repeated warnings that the border could be closed which, in turn, triggered ugly protests that have damaged Scotland’s reputation as a welcoming country.
“It is hard not to conclude that the first minister pushed this unreliable comparison, with no context, for her own political purposes.”
The Scottish government defended the first minister’s use of the data, and said she had used the best available statistics. “The decisions we are taking to ease lockdown restrictions while still suppressing the virus are based on prevalence data,” a spokeswoman said. “It is legitimate to use the evidence that is available to highlight differences in prevalence.”
She added that the Scottish government had been applauded by the Office for Statistics Regulation for regularly releasing more data than the UK government.
“We continue to push the UK government to take the same approach and to publish Covid-19 prevalence statistics that would make this information publicly available.”